Opportunity is an almost identical twin of her sister rover Spirit. She was launched on July 7, 2003, and landed on Mars on Sunday January 24, 2004. At the time that I am writing this she is still operational. She has driven 34,633.40 meters (21.52 miles) as of Sol 3022 (July 24, 2012).
The six wheeled rover has solar arrays that generate about 140 watts for up to four hours per sol, and rechargeable lithium ion batteries shorte energy for use at night. Opportunity, like Spirit, can operate between – 40 Celsius to +40 Celsius. To combat the cold and keep the instruments healthy the rover has radioisotope heaters and electrical heaters. A gold film and a layer of silica aerogel provide insulation to the rover. Communications depends on an omnidirectional low-gain antenna communicating at a low data rate and a steerable high-gain antenna, both in direct contact with Earth. A low gain antenna is also used to relay data to spacecraft orbiting Mars. Opportunity has an identical set of instruments to Spirit. For an explanation of each instrument read the MSL picture of the day blog about Spirit of yesterday.
Right after the successful touchdown of Opportunity Kees Veenenbos and I decided to participate in the Contact conference of that year at NASA Ames that year and drive to Jet Propulsion laboratories for a visit with Nathalie Cabrol. Nathalie is the resident Gusev Crater expert, having studied that particular crater for decades.
Kees had met Nathalie while working on his mars renders for the landing sites. NASA had called upon Kees as space artist to help NASA out with selecting the landing site of the Mars Exploration Rovers. For a while there existed on the web a NASA website that would load slowly because of the 6 renders by Kees being large files. The first thing that would appear on your screen was “© Kees Veenenbos”. To think that a fellow countryman had some skill that NASA needed made our Dutch hearts beat faster. In January 2004 Kees Veenenbos designed the image of the cover of National Geographic, and became the second Dutchman ever to be asked to do that.
At the end of 2004 Kees was also asked to design the image for the cover of the Science Break through number.
Opportunity landed three weeks after its twin, Spirit, during prime time on Saturday night again, at 9: pm in Meridiani Planum. Her spectacular plunge into the atmosphere at about 12,000 MPH was slowed by atmospheric friction on the heat shield and a complex pre-programmed combination of parachutes and retro rockets, and in the last moments by inflatable airbags designed to allow the robot to bounce about two dozen times and gently and gradually roll to a complete stop. When she had stopped bouncing and rolling her landing capsule rested in the Eagle crater only 22 meters wide (72 feet). A hole in one, as Eagle Crater had exposed bed rock. And bed rock is what geologists look for when they want to investigate how a certain region on Earth or Mars came to look like it looks now.
Opportunity had been send to this region because Mars Global Surveyor had discovered a large exposure of the mineral hematite. A mineral which often forms in the presence of water. Measuring infrared radiation (heat) associated with specific minerals, the rovers identified and mapped minerals in rocks and soils. Key among these was hematite in rock outcrops as well as in high concentrations in the rounded, blueberry-size concretions.
During the next few weeks, the rover’s examination of that outcrop settled the long-running debate about whether Mars ever had sustained liquid water on its surface. Opportunity found Goethite, a mineral that only forms when water is involved. We still did not know whether the water in Eagle Crater had been up welling water or streaming water of a brook or river.
Soon that question was answered too as Opportunity found the evidence of running water in the petrified rocks that showed ‘smilies’ = petrified waves indicating to geologists that water had flowed over this region. The texture of the smilies showed that the rocks not only had been saturated with water, but had actually been laid down under gently flowing surface water.
For six months beginning in June 2004, Opportunity examined deeper layers of rock inside a stadium-size crater, Endurance some 700 meters (about half a mile) from the landing site. The wall-rock layers had all soaked in water, but textures in some showed that periods of dry, wind-blown deposition alternated with periods when water covered the surface.
After examining its own jettisoned heat shield and a nickel-iron meteorite near this crater, Opportunity drove more than 4 miles (6 kilometers) southward to reach an even larger and deeper crater, Victoria.
Here, it examined geological evidence of similar environmental conditions from a greater span of time. The presence of sulfur-rich material throughout Opportunity’s study area indicates acidic watery environments.
In mid-2008, Opportunity set off toward Endeavour crater, a crater 22 kilometers (14 miles) in diameter. Orbital observations of Endeavour had detected water-related clay minerals, different from any Opportunity has seen so far and indicative of less-acidic watery environments.
In August 2011, with a total driving odometry of more than 34 kilometers (21 miles), the rover reached the rim of Endeavour Crater to start a new phase of its exploration of Mars. There it found water-deposited veins of gypsum, demonstrating once more the value of mobility and longevity.
6 km west from Endeavour Crater lies Santa Maria crater, which shows spectral signatures of phyllosilicates, or clay bearing minerals, which formed in water about 4 billion years ago and have never before been directly analyzed on the Martian surface.
Opportunity travelled over 34 kilometers over the plains of Meridiani Planum, visiting Eagle Crater were it landed, Endurance Crater, Erebus Crater, Victoria Crater, descended into Victoria Crater and climbed out again, Duck Bay, Endeavour Crater, Santa Maria Crater, to drive to Greeley Haven (part of Endeavour Crater), where it recently left again. The full description of this whole treck and the science involved can be found in the Wikipedia
Together with her twin sister Spirit, the NASA rovers surely rank as one of the greatest feats in the annals of space exploration.